[ARL02-A10] News-TNK Cross Site Scripting Vulnerability

From: Ahmet Sabri ALPER (s_alperat_private)
Date: Sat Mar 16 2002 - 17:01:36 PST

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    +/--------\-------- ALPER Research Labs ------/--------/+
    +/---------\-------  Security Advisory  -----/---------/+
    +/----------\------    ID: ARL02-A10    ----/----------/+
    +/-----------\----- salperat_private  ---/-----------/+
    
    
    Advisory Information
    --------------------
    Name               : News-TNK Cross Site Scripting 
    Vulnerability
    Software Package   : News-TNK
    Vendor Homepage    : http://www.linux-sottises.net/
    Vulnerable Versions: v1.2.1 and older
    Platforms          : Linux
    Vulnerability Type : Input Validation Error
    Vendor Contacted   : 15/03/2002
    Vendor Replied     : 15/03/2002
    Prior Problems     : N/A
    Current Version    : v1.2.2 (immune)
    
    
    Summary
    -------
    News-TNK is script to submit, validate, unvalidate, 
    comment, delete news on a website. Available in 
    French and English at the present time.
    
    A Cross Site Scripting vulnerability exists in 
    News-TNK. This would allow a remote attacker 
    to send information to victims from untrusted web 
    servers, and make it look as if the information 
    came from the legitimate server.
    
    
    Details
    -------
    The URL's and the user input seem to be filtered 
    pretty good. But I guess that the coders have missed 
    a point. The "WEB" input when replying or creating 
    topics, is not filtered enough. So a Cross Site 
    Scripting vulnerability exists in News-TNK.
    
    
    Example input for the "WEB" input
    <script>alert("ALPERz was here!")</script>
    
    After submitting this information, whenever anyone 
    browses the page where the news message is, the 
    malicious code will take effect.
    
    
    Solution
    --------
    The vendor replied to my mail and released a new 
    version which is immune to this vulnerability very 
    quickly (on the same day :})
    
    You may download the new version or use the 
    method suggested by me, and approved by the 
    vendor, if you have made any modifications to the 
    news applet.
    
    Strip HTML tags, and possibly other malicious code 
    within "news_post.php" (or "news_post3.php). 
    
    I suggest the following as a workaround;
    At the beginning of "news_post.php" add the lines 
    below;
    # Patch Start
    $web=strip_tags($web);
    # Patch End
    More info about the new version and patches can be 
    found at: 
    http://www.linux-sottises.net/software.php
    
    
    Credits
    -------
    Discovered on 15, March, 2002 by 
    Ahmet Sabri ALPER 
    salperat_private
    http://www.olympos.org
    
    
    References
    ----------
    Product Web Page: http://www.linux-sottises.net/
    



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